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Successful outcome after total knee arthroplasty (TKA) requires precise realignment of the mechanical axis. The intraoperative assessment of the mechanical axis is difficult. Intraoperatively, the effect of weight bearing on the lower limb mechanical axis is ignored. We developed a custom-made mechanical loading device to simulate weight-bearing conditions intraoperatively and analysed its effect on the mechanical axis during TKA.Measurements of the mechanical axis were obtained during 30 consecutive primary TKAs in osteoarthritic patients using image-free knee navigation system. Half body weight was applied intraoperatively using our device to quantify the effect of intraoperative load application on the mechanical axis, thus receiving indirect information about soft tissue balancing. Furthermore, the intraobserver and interobserver reliability of navigated mechanical axis measurement with and without load was determined.Before TKA, mean mechanical axis was 4.0° ± 4.9° without load. Under loading conditions, the mean change of the mechanical axis was 2.1° ± 2.8°. Repetitive measurements of the senior surgeon and junior surgeon revealed a high intraobserver (ICC 0.997) and interobserver reliability (ICC 0.998). The registration of the mechanical axis without and with application of intraoperative loading demonstrated no significant differences during insertion of the trial components (SD 0.29 ± 0.29) and after the definitive component cementation (SD 0.63 ± 0.44).Intraoperative quantification and analysis of the mechanical lower limb axis applying defined axial loading by our custom-made loading apparatus is reliable. Ligament stability was unbalanced before TKA and balanced after TKA. For TKA, intraoperative simulation of weight bearing may be helpful to quantify, control and correct knee stability and its influence of mechanical axis.

Proper rotational alignment is a critical step of total knee arthroplasty. For intraoperative determination of femoral rotation, Whiteside suggests a perpendicular line to the axis of the center of the trochlea and the intercondylar notch (Whiteside’s line). In a prospective clinical study, the intraoperative position of Whiteside’s line was measured in 30 patients with the help of a navigation system. Whiteside’s line was 2.1° ± 1.5° externally rotated compared to a navigation based computer calculated preliminary AP axis of the femur. The intraobserver-reliability after 3 repeated measurements each was 1.6° for the senior surgeon and 1.4° for the junior surgeon (p = 0.598, p = 0.968). The interobserver reliability between the measurements by the senior and junior surgeon was 1.4° (p = 0.547). Navigated intraoperative measurements of Whiteside’s line showed a high inter- and intraobserver reliability. Considering the variability between Whiteside’s line and the transepicondylar axis, intraoperative assessment of both the methods is recommended.

Die Fraktur des Akromions ist eine seltene, aber schwerwiegende Komplikation, die im Rahmen einer subakromialen Dekompression auftreten kann. Wir berichten uber einen Patienten mit Pseudarthrose des Akromions, der bei Schmerzpersistenz mehrfach operiert wurde, bis es schlieslich zur Diagnose „Pseudarthrose“ kam. Die Pseudarthrose wurde erfolgreich durch Osteosynthese mit einer distalen Radiusplatte und einem monokortikalen Beckenkammspan therapiert. Zwei Jahre nach der Operation sind die Fraktur verheilt und die Beschwerden des Patienten erheblich gebessert. Im Constant Score erreicht der Patient 58 Punkte (praoperativ 25 Punkte) und im Subjective Shoulder Rating System (SSRS) 65 Punkte (praoperativ 25 Punkte). Die Beweglichkeit ist postoperativ deutlich verbessert und betragt fur aktive Abduktion/Adduktion 50/0/25o (30/0/20° praoperativ), fur Ausenrotation/Innenrotation 35/0/45o (30/0/30° praoperativ) und fur Anteversion/Retroversion 60/0/35° (35/0/20° praoperativ).

Introduction: The accuracy of preoperative planning of the size of total knee arthroplasty (TKA) in literature is only 50%. A problem of conventional radiographic planning with prothesis templates is varying enlargement of the radiographs. Digital planning and analysis of lower leg geometry revealed improved reliability compared to conventional techniques. The aim of the study was to evaluate the accuracy of digital planning of TKA with special planning software and calibrated radiographs and its interobserver reliability. Methods: In a prospective study the sizes of 30 TKA were planned with special software by a senior and a junior surgeon independently. For calibration a 30 mm reference ball on the radiographs was used. The planning was compared with the intraoperative chosen size of the TKA. Results: The correlation of the planned femoral component with the chosen size was 87% for the senior and 77% for the junior surgeon. The planning of the tibial component revealed a correlation for the senior surgeon in 90% and for the junior surgeon in 87%. Both component was planned correctly in 77% by the senior and in 63% by the junior surgeon. In 50% the planning of both surgeons matched completely the used prosthesis sizes. The linear κ coefficient of Cohen revealed a good agreement (0.65) and a high interobserver reliability. Discussion: Planning TKA with special planning software with digital, calibrated radiographs is more accurate compared to previous conventional planning. The senior surgeons planning of both component sizes matched in 77% the correct size. Clinical experience improves the accuracy of preoperative planning.

Bone transport can be performed with an external fixator alone or with the monorail technique which entails the combination of a fixator and an intramedullary nail. The purpose of this study was to compare the complication rates and long-term outcomes of these methods. Two groups of patients, the external fixator (n = 21) and the monorail group (n = 18), were compared. The average follow-up period was 7.9 ± 5.6 years and the mean defect length 8.3 ± 3.1 cm. Healing was achieved in 19 (90%) and 13 (72%) of the fixator and monorail patients, respectively. Six patients underwent amputations because of persistent infections (two in the fixator and four in the monorail group). The rate of deformities was significantly higher in the fixator group (p = 0.049). No statistically significant difference was found when comparing categories of the SF-36 test or the ability to work or do sports. The main advantages of the monorail method are reduction of the external fixation time and the lower rate of deformities. However, the authors recommend segmental transport with external fixator in patients with chronic infections.

Press-fit fixation of patellar tendon bone anterior cruciate ligament autografts is an interesting technique because no hardware is necessary. To date, no biomechanical data exist describing an implant-free double-bundle press-fit procedure. The purpose of this study was to characterize the biomechanical properties of three double-bundle press-fit fixations.In a controlled laboratory study, the patellar-, quadriceps- and hamstring tendons of 10 human cadavers (age: 49.2 ± 18.5 years) were used. An inside out press-fit fixation with a knot in the semitendinosus and gracilis tendons (SG) combined with an additional bone block, with two quadriceps tendon bone block grafts (QU) was compared with press-fit fixation of two bone patellar tendon bone block (PT) grafts in 30 porcine femora. Constructs were cyclically stretched and then loaded until failure. Maximum load to failure, stiffness and elongation during failure testing and cyclical loading were investigated.The maximum load to failure was 703 ± 136 N for SG fixation, 632 ± 130 N for QU and 656 ± 127 N for PT fixation. Stiffness of the constructs averaged 138 ± 26 N/mm for SG, 159 ± 74 N/mm for QU, and 154 ± 50 N/mm for PT fixation. Elongation during initial cyclical loading was 1.2 ± 1.4 mm for SG, 2.0 ± 1.4 mm for QU, and 1.0 ± 0.6 mm for PT (significantly larger for PT and QU between the first 5 cycles compared with cycles 15-20th, P 0.01).All investigated double-bundle fixation techniques were equal in terms of maximum load to failure, stiffness, and elongation. Unlike with single-bundle press-fit fixation techniques that have been published, no difference was observed between pure tendon combined with an additional bone block and tendon bone grafts. All techniques exhibited larger elongation during initial cyclical loading. All three press-fit fixation techniques that were investigated exhibit comparable biomechanical properties. Preconditioning of the constructs is critical.

Introduction: Accurate intraoperative assessment of lower limb alignment is crucial for the treatment of long bone fractures, implantation of knee arthroplasties and correction of deformities. Purpose: The aim of this study is to present a new technique for the intraoperative analysis of the mechanical axis. Methods: The axis board is placed under the patient's lower limb. With the centre of the ankle and hip lying on the reference line we can assess the mechanical axis of the lower limb. This technique was used in 38 cases (19 high tibial osteotomies, 13 femoral fractures and 6 tibial fractures). Results: Comparing the intraoperative tibiofemoral angles and Mechanical Axis Deviations (MAD) with the results of the postoperative long standing radiographs we showed an accuracy of 1 ± 0.9° and 2.9 ± 2.6 mm respectively. Conclusion: The method is a simple and convenient option for intraoperative evaluation of the mechanical axis. However, for complex corrections we still recommend the use of navigation systems.

Press-fit-Fixierungen sind interessant, da diese einen zirkularen Kontakt zwischen Knochen und Transplantat ermoglichen und Fremdmaterial vermeiden. Diese Ubersichtsarbeit vergleicht etablierte mit neu entwickelten Press-fit-Fixierungen aller gangigen Transplantate und vergleicht das biomechanische Verhalten mit fremdmaterialhaltigen Fixierungen wie der Interferenzschraube. Fur die Versuche wurden 168 humane Kadavertransplantate entnommen (Alter 49,2±18,5 Jahre). Funfzehn verschiedene Fixierungen wurden miteinander verglichen. Die Konstrukte wurden zyklisch gedehnt und dann bis zum Versagen getestet. Die submaximale Versagenslast, Steifigkeit, Elongation und Versagensart wurden verglichen. Insgesamt zeigen einige Techniken vergleichbare biomechanische Qualitaten wie Fixierungen mit Implantaten. Einige Press-fit-Fixierungen erreichen eine ahnliche Primarstabilitat wie eine Transplantatverankerung mit Implantaten. Durch die gelenknahe Verpressung mit korpereigenem Material erhalt das Transplantat einen engen Kontakt zum gelenknahen kortikalen Knochen.

The long-term outcomes following femoral and tibial segment transports are not well documented. Purpose of the study is to compare the complication rates and life quality scores of femoral and tibial transports in order to find what are the complication rates of femoral and tibial monorail bone transports and if they are different?We retrospectively analyzed the medical records of 8 femoral and 14 tibial consecutive segment transports performed with the monorail technique between 2001 and 2008 in our institution. Mean follow-up was 5.1 ± 2.1 years with a minimum follow-up of 2 years. Aetiology of the defects was posttraumatic in all cases. Four femoral (50%) and nine tibial (64%) fractures were open. The Short Form-36 (SF-36) health survey was used to compare the life quality after femoral and tibial bone transports. The Mann-Whiney U test, Fisher exact test, and the Student's two tailed t-test were used for statistical analysis. P ≤ 0.05 was considered to be statistically significant.The tibial transport was associated with higher rates of severe complications and additional procedures (1.5 ± 0.9 vs. 3.4 ± 2.7, p = 0.048). Three patients of the tibial group were amputated because of recurrent infections and one developed a complete regenerate insufficiency that was treated with partial diaphyseal tibial replacement. Contrary to that none of patients of the femoral group developed a complete regenerate insufficiency or was amputated.Tibial bone transports have a higher rate of complete and incomplete regenerate insufficiency and can more often end in an amputation. The authors suggest systematic weekly controls of the CRP value and of the callus formation in patients with posttraumatic tibia bone transports. Further comparative studies comparing the results of bone transports with and without intramedullary implants are necessary.

Purpose The aim of this study was to analyze the relation between bone mineral density (BMD) and femoral tunnel enlargement (TE) in a previously validated sheep model of soft-tissue anterior cruciate ligament (ACL) reconstruction. Methods Thirty sheep underwent ACL reconstruction by use of a soft-tissue graft at the age of 4 months. Graft fixation was achieved with the EndoButton (Smith & Nephew Endoscopy, Andover, MA) and Suture Washer (Smith & Nephew Endoscopy). Six animals were killed at 0, 3, 6, 12, and 24 weeks postoperatively. Each ACL-reconstructed knee was examined both by computed tomography to analyze the bone tunnel cross-sectional area and by dual-energy x-ray absorptiometry to analyze BMD. Results There was a significant increase in tunnel cross-sectional area. BMD decreased significantly within the first 3 weeks after surgery and increased thereafter. A positive correlation between TE and BMD was found. However, a subgroup analysis showed that there is no influence of BMD on the development of a tunnel widening. Conclusions The hypothesis that a TE would be associated with a loss in BMD was not confirmed. Tunnel widening during the first 6 months after ACL reconstruction is not affected by the transient changes in BMD. Clinical Relevance There is no correlation between TE and BMD in an experimental sheep model of ACL reconstruction. Translational investigations will determine whether this is also true in humans.

Compartment syndrome of the lower leg or foot, a severe complication with a low incidence, is mostly caused by high-energy deceleration trauma. The diagnosis is based on clinical examination and intracompartmental pressure measurement. The most sensitive clinical symptom of compartment syndrome is severe pain. Clinical findings must be documented carefully. A fasciotomy should be performed when the difference between compartment pressure and diastolic blood pressure is less than 30 mm Hg or when clinical symptoms are obvious. Once the diagnosis is made, immediate fasciotomy of all compartments is required. Fasciotomy of the lower leg can be performed either by one lateral incision or by medial and lateral incisions. The compartment syndrome of the foot requires thorough examination of all compartments with special focus on the calcaneal compartment. Depending on the injury, clinical examination, and compartment pressure, fasciotomy is recommended via a dorsal and/or medial plantar approach. Surgical management does not eliminate the risk of developing nerve and muscle dysfunction. When left untreated, poor outcomes with contractures, toe deformities, paralysis, and sensory neuropathy can be expected. In severe cases, amputation may be necessary.Level III. See Guidelines for Authors for a complete description of levels of evidence.

Background Press-fit fixation of a tendon graft has been advocated to achieve tendon-to-bone healing. Hypothesis Fixation of hamstring tendon grafts with a porous bone scaffold limits bone tunnel enlargement compared with a biodegradable interference screw fixation. Study Design Randomized controlled trial; Level of evidence, 1. Methods Between 2005 and 2006, 20 patients (17 men, 3 women) with a primary reconstruction of the anterior cruciate ligament (ACL) were enrolled in this study. Patients were randomized to obtain graft fixation in the tibial tunnel either by means of an interference screw (I) or a press-fit fixation with a porous bone cylinder (P). At 3 months after surgery, a computed tomography (CT) scan of the knee was performed, and tunnel enlargement was analyzed in the coronal and sagittal planes for the proximal, middle, and distal thirds of the tunnel. After 6 months and 1 and 2 years, radiographs of the knee in the sagittal and coronal plane were analyzed for bone tunnel widening. The International Knee Documentation Committee (IKDC), Tegner, and Lysholm scores of both groups were compared after 1 and 2 years. Results The bone tunnel enlargement determined by CT was 106.9% ± 10.9% for group P and 121.9% ± 9.0% for group I (P < .02) in the anteroposterior (AP) plane and 102.8% ± 15.2% versus 121.5% ± 10.1% in the coronal plane (P < .01). The IKDC, Tegner, and Lysholm scores improved in both groups from preoperatively to postoperatively without significant differences between the 2 groups. There was a trend to higher knee stability in group P after 3 months (0.6 ± 1.4 mm vs 1.8 ± 1.5 mm; P = .08). Conclusion Both interference screw and a press-fit fixation lead to a high number of good or very good outcomes after ACL reconstruction. Tibial press-fit fixation decreases the amount of proximal bone tunnel enlargement.

High tibial osteotomy is an established technique for the treatment of varus malaligned knees. This study analyses the difference between the amount of correction in the preoperative planning and the postoperative result. Furthermore, it compares the difference of the accuracy between open-wedge osteotomy and closed-wedge osteotomy. About 61 patients were either treated with open-wedge or closed-wedge high tibial osteotomy. Preoperative planning and postoperative analysis were performed with a special planning software. The influence of operative technique, aetiology, age, number of previous surgeries, amount of correction and accuracy of the correction compared to the preoperative planning were analysed. The overall postoperative mechanical axis differed form preoperative planning by 2.1° ± 1.7°. The accuracy in the open-wedge group (1.7° ± 1.6°) was significantly higher than in the closed-wedge group (2.6° ± 1.8°; P = 0.038). In patients with congenital varus deformity, the accuracy of the correction was significantly higher than in patients with post-traumatic deformity. The authors recommend open-wedge technique in combination with fixed-angle plates for high tibial osteotomy.

Controversy exists in the literature regarding the most appropriate treatment for anterior cruciate ligament (ACL) ruptures in the skeletally immature patient. To study the histological and biomechanical stages following ACL reconstruction during growth, it is necessary to establish an equivalent model to replicate the situation of an immature skeleton. In the present study we evaluated a large animal model of ACL reconstruction during growth using skeletally immature sheep. In contrast to existing models we did not intend to provoke growth disturbances. Instead, we identified those criteria known to be essential to prevent growth disturbances in the human situation and transformed them into an animal model. Applying those criteria to skeletally immature sheep at an age of four months, we performed a fully transphyseal ACL reconstruction of their right knee. The contralateral knee served as a control. The sheep were then sacrificed 3, 6, 12 and 24 weeks after surgery. This animal model is described in detail in the present manuscript. Basic science data are presented in order to 1) make it easier for other research groups to study ACL reconstruction during growth using our model and 2) to improve this model by modifying the one or other detail of the proposed technique. Using this model, remaining open questions concerning ACL reconstruction during growth can be addressed in future studies.

In the present study, the long-term results of 11 patients with anterior sternoclavicular joint (SCJ) instability are reported. All included patients had an anterior SCJ instability and due to delayed diagnosis, operative treatment was not done immediately. The patients had a mean age of 29.2 years (range 16–63 years). One patient sustained concomitant injuries. Six patients had resection arthroplasty. Five patients had reconstruction of the SCJ with transosseous tension band PDS fixation or ligament reconstruction with additional wire cerclage. The results of treatment were evaluated after a mean follow-up period of 9.9 years (range 1–27 years) using the ASES, DASH and power-, age and gender adjusted Constant–Murley Score. In general, the mean values of the different scores (ASES 79.8; DASH 11.8; Constant–Murley 81%) demonstrated good outcome. The outcome evaluation of the patients who had SCJ reconstruction did not differ significantly from the patients who had medial resection arthroplasty. The rate of postoperative pain or instability was low using visual analog scale and did not differ significantly between the groups. The outcome results of the reconstruction group were equal to the results of the resection group when SCJ-reconstruction was performed soon after SCJ injury. One patient in the resection group (6 patients) demonstrated poor results due to continued instability of the remaining clavicle. We concluded that patient selection and a specific clinical indication for operative treatment are crucial. Resection of the medial clavicle results in good functional outcome when the costoclavicular ligament is preserved or reconstructed.

Zusammenfassung Fragestellung Ziel dieser Arbeit war, zu uberprufen, in wieweit eine routinemasige Durchfuhrung praoperativer Magnetresonanztomographie (MRT)-Untersuchungen vor Kniegelenksarthroskopien die Indikationsstellung verbessern und die Rate rein diagnostischer Arthroskopien verringern kann. Methoden Es wurden Daten von je 1000 Patienten analysiert, welche sich 1994/95 und 2004/05 einer Kniearthroskopie unterzogen hatten. In die Untersuchungsgruppen wurden alle Patienten unselektiert in fortlaufender Reihenfolge einbezogen. Untersucht wurde die Ubereinstimmung (Kongruenz) der praoperativen Diagnosen mit den intraoperativen Befunden. Alle Befunde (praoperative Verdachtsdiagnosen und MRTs) sowie standardisierte Operationsberichte lagen (EDV) schriftlich vor. Ergebnisse Die Anzahl der MRT-Untersuchungen war in zehn Jahren von 23,7% auf 56,5% gestiegen. Die Ubereinstimmung von praoperativer und intraoperativer Diagnose hatte sich um ca. 6% gebessert. Bei den vermeidbaren diagnostischen Eingriffen hatte sich mit 2,6% gegen 3% keine signifikante Anderung durch vermehrten Einsatz der MRT ergeben. Schlussfolgerung Die typischen und haufigen Indikationen zur Kniearthroskopie benotigen neben Anamnese sowie klinischer und nativradiologischer Untersuchung routinemasig kein MRT zur Indikationsstellung. Das MRT des Kniegelenkes sollte speziellen Fragestellungen vorbehalten bleiben. Es ermoglicht eine genauere Einschatzung der zu erwartenden Befunde und kann z.B. strategischen Aspekten bei der Therapieplanung dienen.

Background There is a lot of controversy in the recent literature with regard to the optimal treatment of anterior cruciate ligament (ACL) injuries during growth. Iatrogenic growth disturbance due to physeal damage is a potential complication, forcing many orthopaedic surgeons to treat these injuries conservatively. Hypothesis It is possible to perform a fully transphyseal ACL reconstruction in an ovine model with wide-open physes without creating growth disturbances. Study Design Descriptive laboratory study. Materials and Methods Four-month-old skeletally immature sheep underwent a transphyseal ACL reconstruction of the right knee. The surgical technique followed the criteria known to be essential to avoid growth disturbances in humans; the tibial tuberosity was spared to prevent a genu recurvatum, thermal damage to the growth plates was avoided, the physes were perforated with a small-diameter drill in the center of the growth plate, a soft tissue graft was used, graft fixation was achieved far away from the growth plates, the perforated growth plates were filled by the soft tissue graft, and the graft was moderately pretensioned before fixation. The left knee served as a control. A computer-assisted evaluation of long radiographs (frontal and sagittal plane) of the exarticulated hindlimbs was performed to exactly evaluate the limb alignment, joint orientation, and leg length. The animals were sacrificed in groups of 6 after 3, 6, 12, and 24 weeks. Results No angular deformities or leg-length discrepancies occurred after this transphyseal ACL reconstruction procedure throughout the remaining growth. Conclusion This large-animal study supports the clinical observation that it is possible to perform an ACL reconstruction without creating growth disturbances as long as a number of key principles are followed. Clinical Relevance Previous animal studies argued against ACL reconstruction in skeletally immature patients. This large-animal study provides support for early operative treatment of ACL ruptures even in young patients with open physes.

Uberpruft werden sollte eine vereinfachte Operationstechnik der Suspensionsarthroplastik bei Rhizarthrose mit kurzstreckiger Praparation der Flexor carpi radialis Sehne. Es wurden 52 Patienten retrospektiv analysiert, bei welchen zwischen 1997 und 2006 63 Suspensions-Arthroplastiken in modifizierter Technik durchgefuhrt worden waren. Bei dieser Technik wurde eine langstreckige Praparation der flexor carpi radialis Sehne vermieden. Es wurde lediglich der ca. 3cm lange Sehnenanteil, welcher primar in situ sichtbar ist, halftig gespalten und distal gestielt. Die gestielte, fadenarmierte Sehnenhalfte wurde pressfit mit transossarer Naht in einem schragen Bohrloch der MC 1 Basis verankert. Postoperativ wurde fur 3 Wochen in einer Gipsschiene ruhiggestellt, anschliesend 3 Wochen Orthesenbehandlung mit zunehmender Mobilisation. Bei 10 Patienten wurde intraoperativ der Abstand Basis MC 1 – Skaphoid mit und ohne Suspension gemessen. Analysiert wurde bei kompletter Datenlage der postoperative Verlauf klinisch und radiologisch und das Ergebnis nach 3 Monaten. Bei 49 Patienten konnten wir nach 1–7 Jahren eine Nachuntersuchung durchfuhren. Postoperativ ergab sich mit einer revisionsbedurftigen Nachblutung nur eine Komplikation. Subjektiv waren 48 von 52 Patienten (60 operierte Hande) zufrieden bis sehr zufrieden. Objektiv sahen wir fur 53 (88 %) Operationen ein gutes bis sehr gutes Funktionsresultat. Schlechte klinische Ergebnisse wurden nicht gefunden. Nur ein Patient wurde die Operation nicht wieder durchfuhren lassen. Der Abstand MC 1 Basis – Skaphoid betrug intraoperativ ohne Suspension 2–5 mm, mit Suspension 9–12 mm. Der radiologische Abstand zwischen Metacarpale I und distaler Scaphoidbegrenzung betrug nach 1–7 Jahren zwischen 4 mm und 9 mm ebenso wie nach 3 Monaten. Die oben beschriebene Modifikation der Suspensionsarthroplastik mit kurzstreckiger Mobilisation der flexor carpi radialis Sehne vermindert die Zugangsmorbiditat und fuhrt zu einer stabilen Suspension, so dass eine Gipsruhigstellung uber 3 Wochen unnotig ist. Fruhzeitig werden gute Funktionsresultate erreicht.

We present the case of a 62-year-old man with posttraumatic osteoarthritis after a tibial head fracture. A below-knee amputation of the same limb had been performed years ago because of a chronic diabetic foot ulcus. The patient underwent total knee replacement, and the 2-year postoperative clinical outcome was very good. The problem of how to address missing anatomic reference points for the implantation of the tibial component in below-knee amputees and the question whether navigation offers a potential benefit in this situation are discussed.

Successful outcomes following high tibial osteotomy (HTO) require precise realignment of the mechanical axis of the lower extremity. The inability to accurately assess the weight-bearing axis intraoperatively may account for inappropriate degrees of correction with the osteotomy. We tested the hypothesis that axial loading of the limb affects alignment during an HTO procedure. A custom mechanical load apparatus was developed to simulate weight-bearing conditions intraoperatively. Fixation to the trunk was achieved by supraacetabular pins and an external fixation device, which allowed the pelvis to be rigidly fixed relative to the apparatus while axial load was applied to the foot. Ten fresh cadavers were used for testing. The baseline mechanical axis was determined by a navigation system. HTO was then performed, and varying degrees of valgus correction were obtained and stabilized. For each correction, one quarter, one half, or full body weight was applied axially to the foot, and the axis deviation was measured. Subsequently, the MCL was sequentially released to determine the effect of ligament incompetence. Prior to osteotomy, load application did not produce significant axis deviations. Following osteotomy, the mechanical axis deviation shifted significantly in all trials, increasing as load magnitude and degree of correction increased. With complete sectioning of the MCL, a further significant shift in the axis occurred. Deviations of mechanical axis occur on weight bearing in lower limbs following HTO. These shifts must be considered and possibly quantified to achieve the desired axis correction and maximize the chance at a successful long term outcome.

Summary Injection of bone marrow stem cells in a liquid fibrin matrix in a patellar tendon window defect significantly improved the healing process in an animal study. Tissue samples of untreated tendon defects, and defects treated with fibrin matrix without cells, revealed less mature healing tissue with reduced biological and biomechanical properties. In contrast to the treatment with bone marrow stem cells, defects filled with a mixture of fibroblasts and liquid fibrin matrix increased collage fibrin diameter, but did not influence the molecular biological and biomechanical results significantly. Tissue Engineering with bone marrow stem cells in liquid fibrin matrix may be a new treatment option to improve the compex process of tendon and ligament healing and the clinical results of tendon and ligament injuries.

The original complex structure and mechanical properties are not fully restored after ligament and tendon injuries. Due to their high proliferation rate and differentiation potential, Bone Marrow Stromal Cells (BMSC) are considered to be an ideal cell source for tissue engineering to optimize the healing process. Ideal matrices for tissue engineering of ligaments and tendons should allow for homogenous cell seeding and offer sufficient stability. A mixture of human BMSC and liquid fibrin glue was injected into a standardized full-thickness window defect of the patellar tendon of immunodeficient rats (BMSC group). The histology of the tissue was analysed 10 and 20 days postoperatively and compared to four control groups. These groups consisted of a cohort with a mixture of human fibroblasts and fibrin glue, fibrin glue without cells, a defect group without treatment, and a group with uninjured patellar tendon tissue. Tendon defects in the BMSC group revealed dense collagen fibres and spindle-shaped cells, which were mainly orientated along the loading axis. Histologic sections of the control groups, especially of untreated defects and of defects filled with fibrin glue only, showed irregular patterns of cell distribution, irregular formed cell nucleoli and less tissue maturation. Compared to healthy tendon tissue, higher numbers of cells and less intense matrix staining was observed in the BMSC group. No ectopic bone or cartilage formation was observed in any specimen. Injection of human BMSC in a fibrin glue matrix appears to lead to more mature tissue formation with more regular patterns of cell distribution. Advantages of this “in-vivo” tissue engineering approach are a homogenous cell-matrix mixture in a well-known and approved biological matrix, and simple, minimally-invasive application by injection.

Inaccurate coronal plane realignment is a common problem after high tibial osteotomy. It has been shown that lower limb rotation has an effect on the two-dimensional measurement of lower limb alignment. Although alignment errors are known to occur due to limb rotation, the magnitude of this effect is unknown. Navigation systems allow for the measurements of coronal plane alignment and dynamically rotational and sagittal plane. Our study evaluated the effect of rotational leg movements on coronal plane alignment as determined by image-free navigation. We hypothesized that a linear relationship exists between rotation and angular measurements. Eight cadavers were used, while three test conditions of the complete lower limbs were established: (1) solid knee arthrodesis, (2) provisional knee arthrodesis and (3) unconstrained knee conditions. Navigated measurements of coronal and sagittal lower limb axis were done initially without knee flexion for defined internal/external rotations of 5 degrees, 10 degrees and maximal values for all test series. Repeated test for the unconstrained knee included stepwise knee flexion of 5 degrees, 10 degrees and 20 degrees. Statistical analysis comparing the test conditions 1, 2 and 3 and comparison between flexion movements of the unconstrained knee were done. Results revealed no significant differences between the different rotations of test condition 1 (mean 0.34 degrees, SD 0.23, range, 0 degrees-0.8 degrees). Condition 2 similarly did not result in significant deviations (mean 0.51 degrees, SD 0.24, range 0.1 degrees-0.9 degrees). Measurement deviations ranging from 0.4 degrees to 4.3 degrees were found for condition 3, the unconstrained knee. However, no statistically different testings from the arthrodesed knee were found (P=0.099-0.410). Knee flexion from 5 degrees, 10 degrees or 20 degrees, showed significant deviations (P0.05) for all rotations at all degrees of flexion. Rotation and flexion of 5 degrees led to significant alignment errors of 3.4 degrees and 2.8 degrees, respectively, for internal and external rotations. Measurement failures due to the rotational movements of 1 degree-4 degrees might add to additional sources of errors causing relevant under- or over-corrections of the mechanical leg axis. Discrepancies of the axis due to rotational movements as well as flexion of the knee joint can be avoided and corrected immediately with the help of navigation.

Entfernung von geschadigtem Meniskusgewebe und damit mechanischer Hindernisse der Gelenkbewegung. Moglichst viel funktionell intaktes Meniskusgewebe soll erhalten bleiben. Nur so viel Resektion wie notig. Traumatisch oder degenerativ bedingte, symptomatische, nicht rekonstruierbare Meniskuslasionen. Rekonstruierbare Meniskuslasionen. Lokale Hautaffektionen. Einbringen des Arthroskops uber einen anterolateralen oder zentralen Zugang. Platzierung eines Instrumentenzugangs in Abhangigkeit von der Lokalisation der zu bearbeitenden Meniskuslasion. Das zu entfernende Meniskusgewebe wird entweder mit unterschiedlichen Stanzen fragmentiert oder en bloc reseziert. Funktionelle Nachbehandlung ohne Ruhigstellung. Vollbelastung des Beins. Nach arthroskopischer Meniskusteilresektion konnen kurz- und langerfristig sehr gute und gute klinische Ergebnisse erreicht werden. In einer Studie von Burks et al. hatten 146 Patienten mit stabilen Kniegelenken 14,7 Jahre nach partieller Meniskektomie in 88% der Falle ein sehr gutes und gutes Resultat. Von 57 Patienten mit partieller medialer Meniskektomie waren nach 12 Jahren 95% mit dem Ergebnis zufrieden oder sehr zufrieden. Ein degenerativer Meniskusriss, eine Achsenfehlstellung, hoheres Alter und eine vordere Kreuzbandinsuffizienz sind langerfristig mit einer erhohten Arthroserate assoziierte Faktoren.

The first clinical experiences with a computer assisted surgery based (CAS) guided correction arthrodeses at ankle, hindfoot and midfoot were evaluated. Methods Time spent, accuracy, surgeons' rating (Visual Analogue Scale [VAS], 0–10 points) were analyzed. The accuracy was assessed by ISO-C 3D (Siremobile™, Siemens, Germany). Results 10 patients were included (ankle, n =3; subtalar joint, n =6; ankle and subtalar joint, n =2; Lisfranc joint, n =1). Time needed for preparation was 500s (400–900). The correction process took 45s (30–60). All angles/translations were achieved as planned before surgery (≤±1°/±1mm). The ratings of the three involved surgeons were: feasibility, 9.5 (9–10); accuracy 9.8 (9.5–10); clinical benefit 9 (8–10). Conclusions CAS guided correction of posttraumatic deformities of the ankle and hindfoot region provides very high accuracy and a fast correction process. The significance of the introduced method may be high in those cases, because the improved accuracy may lead to an improved clinical outcome.

We prospectively followed a case series of 68 patients with 69 AO/ASIF 41-C-type fractures treated with the Less Invasive Stabilization System for the proximal lateral tibia. We assessed malreduction, secondary loss of reduction, and infection rates in patients with a locked screw plate for unilateral fixation of bicondylar fractures. Sixty-two (91%) patients returned for final followup (range, 11-13 months). Malreduction and malalignment were defined as an intraarticular step-off of 2 mm or greater, or as a malalignment in the frontal or sagittal plane greater than 5 degrees . Fourteen fractures were open. Primary bone grafting was done in 13 patients. Significant malreduction was seen in 16 patients. There were four superficial infections and one deep infection. One fracture did not heal, and nine patients had substantial loss of reduction. Unilateral locked screw plating is a good alternative for treatment of problematic fractures of the tibial plateau that are associated with soft tissue damage and metaphyseal comminution. The reduction technique for exact alignment is demanding.

Die routinemasige Entfernung von Tibiamarknageln nach Frakturheilung war jahrelang empfohlen. Das Ziel dieser Studie war es, Empfehlungen zur Indikationsstellung fur die Entfernung von Tibiamarknageln zu erarbeiten. Es wurde eine retrospektive Analyse von 69 isolierten Implantatentfernungen nach Frakturheilung durchgefuhrt. Hierzu wurden Akten und Rontgenaufnahmen der Patienten untersucht. Als Follow-up erfolgte ein Telefoninterview bei 44 (64%) Patienten. Von den 26 Patienten, die vor der Operation Beschwerden hatten, gaben 19 (73%) eine Verbesserung der Symptomatik an. 11% (n=5) aller Patienten berichteten jedoch uber eine Verschlechterung der Symptomatik durch die Operation. 3 Patienten (17%), die zuvor beschwerdefrei waren, hatten Beschwerden durch die Operation. In der vorliegenden Studie hatten weder die Nageltiefe noch der Gebrauch einer Verschlusskappe noch die Qualifikation des Operateurs noch das Intervall zwischen Nagelinsertion und Entfernung Einfluss auf die Operationszeit. Die routinemasige Entfernung von Tibiamarknageln bei asymptomatischen Patienten sollte kritisch mit diesen diskutiert werden.

Kallusdistraktion von Femur oder Tibia durch ein intramedullares Implantat, welches sich mechanisch durch alternierende Rotationsbewegungen von mindestens 3° verlangert. Beinverkurzungen des Femurs oder der Tibia zwischen 20 und 80 mm. Gleichzeitige Korrektur von Achsendeformitaten im Bereich der Osteotomie moglich. Offene Wachstumsfugen. Unzureichender Markrauminnendurchmesser (nach Aufbohrung des Femurs < 14,5 mm, der Tibia < 12,5 mm). Mangelnde Mitarbeit des Patienten. Ausgepragte Fehlstellungen. Osteitis. Weichteilinfekte. Ruckenlagerung. Am Femur im proximalen oder mittleren Schaftdrittel Osteotomie nach facherformigen queren Anbohrungen, unter Rotationskontrolle mit zwei 3,0-mm-Kirschner-Drahten. An der Tibia quere Osteotomie mit einer Gigli-Sage. Korrektur von Achsen- oder Rotationsfehlstellungen. Antegrades Aufbohren der Markhohle am Femur 2,0 mm, an der Tibia 1,5 mm uber den geplanten Nageldurchmesser. Einfuhren des Intramedullary Skeletal Kinetic Distractor (ISKD) in den Markraum, distale Verriegelung in Freihandtechnik, Kontrolle der Rotation sowie des Osteotomiespalts und proximale Verriegelung mit einem Zielgerat. Intraoperative Kontrolle der Distraktion des ISKD uber einen externen Monitor. Am Femur 3 Tage und an der Tibia 5 Tage postoperativ Beginn zunehmender Mobilisation, um eine tagliche Distraktion von etwa 1 mm zu erreichen. Bei unzureichender Verlangerung fuhrt der Patient gezielte Rotationsbewegungen durch, bis die erwunsche Verlangerung erreicht ist. Vier Patienten mit einem mittleren Alter von 29 Jahren (18–36 Jahre) wurde ein ISKD implantiert. Neben drei posttraumatischen Femurverkurzungen wurde eine kongenitale Tibiaverkurzung behandelt. Zwei Femora wiesen praoperativ komplexe Fehlstellungen auf. Die durchschnittliche Verlangerung betrug 31 mm (26–40 mm). Der intraoperative Blutverlust betrug 230 ml (100–320 ml), die durchschnittliche Operationszeit 108 min (90–145 min). Die tagliche Distraktionsstrecke belief sich im Durchschnitt auf 1,2 mm (0,9–1,8 mm). Vollbelastung wurde nach 10 Wochen (7–14 Wochen) gestattet, Arbeitsfahigkeit bestand nach 11 Wochen (7–16 Wochen). Bei der Nachuntersuchung durchschnittlich 2,3 Jahre postoperativ bestanden keine Einschrankungen der Kniegelenkbeweglichkeit. Das Kallusregenerat war 80 Tage (51–111 Tage) nach der Operation knochern durchbaut bei einem mittleren Heilungsindex von 2,9 Tagen/mm (1,8–4,1 Tage/mm). Innerhalb des Beobachtungszeitraums waren keine Komplikationen aufgetreten. Gemas dem Paley-Score erreichten alle Patienten ein exzellentes Ergebnis.

Die Kallusdistraktion basiert auf dem Prinzip, durch kontinuierliche Distraktion eines sich bildenden Kallus Knochengewebe zu regenerieren. Sie hat sich als Standardverfahren bei ausgedehnten Beinverkurzungen sowie langstreckigen Knochendefekten etabliert. Die Behandlung ist aufwandig und komplikationstrachtig und bedarf einer exakten Planung, Operationstechnik sowie sorgfaltigen Nachbehandlung. Externe Fixateure sind universell einsetzbar, verursachen durch die Weichteiltransfixation allerdings Pininfekte, Schmerzen und Bewegungseinschrankungen mit entsprechender Limitierung der Aktivitat. Sie werden daher vorzugsweise bei erhohtem Infektrisiko, simultaner Verlangerung mit kontinuierlicher Achsenkorrektur und bei offenen Wachstumsfugen eingesetzt. Beim Monorail-Verfahren wird die Fixateurtragedauer verkurzt, indem die Kallusdistraktion mit einem Fixateur externe uber einen Marknagel erfolgt, und der Fixateur nach Abschluss der Distraktion entfernt wird. Die intramedullare Schienung schutzt das Kallusgewebe vor Refrakturen und Achsenabweichungen. Neu entwickelte Verlangerungsnagel ermoglichen nunmehr eine vollstandig interne Kallusdistraktion und eine rasche Wiederaufnahme taglicher Aktivitaten. In dieser Ubersichtsarbeit werden Prinzipien der Kallusdistraktion, Komplikationsmoglichkeiten sowie deren Management dargestellt.

Introduction: Limb lengthening by external fix- ators is associated with many problems such as pain at the pin tracts, muscle transfixation, pin tract infections, re- duced joint motion, and prolonged fixation time. The in- tramedullary skeletal kinetic distractor (ISKD) is a new internal, mechanically activated implant, which distracts by mild rotations of 3°. Material and methods: In a prospec- tive clinical study, four patients with an mean age of 29 years (18-36 years) underwent intramedullary length- ening via ISKD. The average lengthening of three femora and one tibia was 31 mm (26-40 mm). Results: All pa- tients performed the rotations for the distraction them- selves without any significant problems. One patient took mild analgesics during the first days of distraction, whereas three patients did not require any analgesics. The average patient discharge occurred 10 days (8-11 days) postopera- tively with no complications during the hospital stay. The planned length of distraction was achieved in all patients with normal alignment and normal joint orientation. Full weight bearing was performed on average after 10 weeks (7-14 weeks). Consolidation was noted 80 days (51-111 days) postoperatively with an average consolidation index of 2.9 days/mm. No complications were observed during the follow-up period of 14 months. The Enneking score was 26.8 points, and according to the classification of Paley all patients had an excellent result. Conclusions: From these preliminary results we conclude that the comfort of limb lengthening with the ISKD is increased by the elimination of fixator-associated complications and by the simple dis- traction mechanism, which is well tolerated by the pa- tients. Further advantages of the ISKD are early full weight bearing and excellent limb function.

Die Focal-dome-Osteotomie (FDO) ist eine zylindrische Osteotomie, deren korrespondierende Knochenenden ineinander um das Zentrum der Deformitat gleiten. Hierdurch kann eine vollstandige, achsengerechte Korrektur ohne unerwunschte Translationsabweichungen erreicht werden. Die FDO ermoglicht eine hohe intraoperative Justierbarkeit, einen optimalen Knochenkontakt sowie eine hohe Primarstabilitat. Ahnlich wie bei „Opening-wedge-“, „Closing-wedge-“ und „Neutral-wedge-Keilosteotomien“ konnen FDO als neutrale, offnende und schliesende Osteotomien durchgefuhrt werden. Aufgrund der domformigen Osteotomie sind offnende FDO unter Erhalt des Knochenkontaktes und schliesende FDO ohne Verlust von Knochensubstanz moglich. Interligamentare FDO konnen durch Valgisierung gleichzeitig zu einer Straffung des Knieinnenbandes fuhren. Infratuberositare FDO beeinflussen ublicherweise die Funktion des Patellofemoralgelenks nicht und minimieren das Risiko intraartikularer Frakturen. Sofern das gelenknahe Fragment eine ausreichende Lange aufweist, ist eine Stabilisation mit einem Verriegelungsnagel moglich. Auch fur hohergradige Fehlstellungen in der Frontal- und Sagittalebene stellt die kniegelenknahe FDO eine hervorragende Therapieoption dar.

Die optimale Therapie der Osteochondrosis dissecans tali (ODT) wird aktuell sehr kontrovers diskutiert. Neben knochenmarkstimulierenden, faserknorpelinduzierenden Verfahren wie der Abrasionsplastik, Herdanbohrung und Mikrofrakturierung werden in zunehmendem Ausmas die autologe osteochondrale Transplantation und autologe Chondrozytentransplantation eingesetzt. 10,4 Jahre nach knochenmarkstimulierender Therapie wurden 45 Sprunggelenke von 44 Patienten mit einer ODT im Stadium 3 und 4 nach Berndt und Harty nachuntersucht und die Ergebnisse mit dem AOFAS-Score, Mazur-Score sowie der radiologischen Klassifikation von van Dijk analysiert. An allen Sprunggelenken war das Dissekat entfernt und eine Abrasion des subchondralen Knochens durchgefuhrt worden sowie in 67% eine zusatzliche antegrade Herdanbohrung erfolgt. Die maximale Ausdehnung der Lasion betrug praoperativ durchschnittlich 1,1 cm. Ein exzellentes funktionelles Resultat wurde im Score von Mazur bei 28 Patienten (62%) beobachtet, bei 12 Patienten (27%) ein gutes und bei 5 (11%) ein masiges oder schlechtes Resultat. Der durchschnittliche AOFAS-Score betrug 91 Punkte (66–100 Punkte). An 8 Gelenken (18%) waren innerhalb des Beobachtungszeitraumes weitere operative Eingriffe erforderlich. Progressive osteoarthrotische Veranderungen gemas der Klassifikation von van Dijk wurden an 7 Sprunggelenken (16%) nachgewiesen. Patienten uber 40 Jahre, mit Adipositas sowie vorbestehenden osteoarthrotischen Veranderungen erreichten signifikant schlechtere Ergebnisse im AOFAS- und Mazur-Score. Die knochenmarkstimulierende Therapie der ODT im Spatstadium ist ein gunstiges,wenig invasives Verfahren und stellt zumindest bei kleineren ODT-Lasionen eine gute Behandlungsoption dar. Neuere Verfahren wie die autologe osteochondrale Transplantation und autologe Chondrozytentransplantation fuhren zu uberwiegend guten und sehr guten 2- bis 4-Jahres-Ergebnissen, haben jedoch ihre Uberlegenheit im Langzeitverlauf noch nachzuweisen.

Die Rekonstruktion langstreckiger knocherner Defekte stellt eine chirurgische Herausforderung dar.Diese Kasuistik beschreibt die Hemikallotasis des Femur durch einen Halbschalensegmenttransport zur Rekonstruktion eines 6 cm langen Femurschaftteildefekts,welcher nach Sanierung einer posttraumatischen Osteitis entstanden war. Diskutiert werden Anwendungsmoglichkeiten dieses Verfahrens, Modifikationen,Vorteile, potenzielle Probleme und alternative Methoden.

Background and Objective: The aim of this retrospective study was to evaluate the outcome of short-segment dorsal stabilization and fusion with transpedicular bone grafting with regard to the success of correction and the functional results in fractures of the lower lumbar spine. Patients and Methods: Out of 39 patients with a fracture of the third to fifth lumbar vertebra treated operatively, 31 were followed up clinically and radiologically over an average period of 26 months (12–61 months). Parameters describing changes at the fracture level and in the adjacent intervertebral spaces were measured by means of imaging investigations. The functional results of treatment were also recorded and compared to the radiologic data. Results: The correction observed radiologically showed a different pattern depending on the fracture level. In fractures of the third and fourth lumbar vertebrae, there was marked vertebral wedging on the one hand, while, on the other hand, there was a considerable loss of correction postoperatively, particularly in the cranial intervertebral space. Finally, the kyphotic angle at the time of follow-up did not differ significantly from the preoperative levels. On the other hand, marked vertebral wedging was not observed in fractures of the fifth lumbar vertebra. In these fractures, the radiologic parameters therefore did not demonstrate significant changes throughout the course. Four patients (12.9%) had an incomplete neurologic deficit preoperatively. An improvement of at least one Frankel stage was observed subsequently in three of these patients. However, postoperative neurologic complications were found in two patients (6.4 %) in whom the initial neurologic examination was unremarkable. The radiologic parameters did not correlate with the functional results. The functional result was classified as satisfactory in 29 patients (93.5%), yet as unsatisfactory in two (6.4%). Conclusions: Stable restoration of regional lordosis could be not achieved with the operative procedure that was employed. This procedure is also characterized by a high rate of complications and cannot be recommended in future. In particular, conservative treatment methods appear to be a sensible alternative.

OBJECTIVE To describe a new method for femoral rotational alignment during intramedullary nail insertion using the profile of the greater trochanter and its relation to the femoral head. METHODS Radiologically, the line that represents the posterior border of the greater trochanter comes in contact with the femoral head contour during external rotation. The degree of rotation to achieve this contact was measured on both lower extremities of 15 whole fresh-frozen cadavers and seven dried human femora using a standard image intensifier. Computed tomography was used in the dried femora to assess the femoral anteversion angle, the length of the femoral neck, and the neck-shaft angle. RESULTS The side difference of the greater trochanter-head contact angle was 6° or less in 14 of 15 whole fresh-frozen cadavers. Regarding the dried human femora, this angle had a strong positive correlation with femoral neck anteversion angle (r = 0.9), whereas no statistically significant correlation could be detected with the neck length or the neck-shaft angle. CONCLUSION Our described method is simple to execute because it depends on a definite point of measurement. Furthermore, an angle is recorded for each extremity, which enables us to estimate the amount of the rotational difference. This method does not depend on special views, especially at the hip, but only a direct anteroposterior view with gradual internal rotation of the image intensifier.

The purpose of this prospective study was to investigate the practicality, accuracy, and reliability of upright MR imaging as a new radiation-free technique for the measurement of mechanical axis.We used upright MRI in 15 consecutive patients (30 limbs, 44.7 ± 20.6 years old) to measure mechanical axis deviation (MAD), hip-knee-ankle (HKA) angle, leg length, and all remaining angles of the frontal plane alignment according to Paley (mLPFA, mLDTA, mMPTA, mLDTA, JLCA). The measurements were compared to weight bearing full length radiographs, which are considered to be the standard of reference for planning corrective surgery. FDA-approved medical planning software (MediCAD) was used for the above measurements. Intra- and inter-observer reproducibility using mean absolute differences was also calculated for both methods.The correlation coefficient between angles determined with upright MRI and weight bearing full length radiographs was high for mLPFA, mLDTA, mMPTA, mLDTA, and the HKA angle (r0.70). Mean interobserver and intraobserver agreements for upright MRI were also very high (r0.89). The leg length and the MAD were significantly underestimated by MRI (-3.2 ± 2.2 cm, p 0.001 and -6.2 ± 4.4 mm, p = 0.006, respectively).With the exception of underestimation of leg length and MAD, upright MR imaging measurements of the frontal plane angles are precise and produce reliable, reproducible results.

The effect of the rotational alignment of lower extremities on the tibiofemoral contact mechanics is not known. This study was designed to measure the contact area and pressure within medial and lateral tibiofemoral compartments following controlled serial rotational deformities through femoral and tibial shafts.Eight lower extremities of fresh frozen cadavers were used. Computed tomography was conducted to measure the rotational profile of the lower extremities. Through a medial parapatellar arthrotomy, pressure sensors were implanted into both tibiofemoral compartments. Femoral and tibial mid-shaft osteotomies were performed and stabilized by non-locked intramedullary nails and external fixators in neutral rotation. The contact area and pressure were measured under axial loading in neutral rotation and following serial malrotations from 40° external to 40° internal malrotation in 10° increments.Contact area was not affected by malrotations. Medial compartment contact pressure rose with external and decreased with internal malrotations whether femoral or tibial (P 0.0001) while lateral pressure was not affected. When correlated with the cadavers' original rotational profile, decreased femoral neck anteversion was associated with increased medial pressure up to 28.5% at 20° of retroversion while it decreased with increased anteversion. On the other hand, decreased tibial torsion angle was associated with decreased medial pressure up to -32% at 10° of internal torsion and it increased with excessive external torsion. Furthermore, there was a strong positive correlation with the total rotational alignment as measured by the neck malleolar angle.A significant interaction could be detected between the rotational alignment of the lower extremity and medial tibiofemoral compartment contact pressures.

Background Mechanically activated intramedullary lengthening nails are advantageous over external fixator. However, difficulties with the control of the distraction rate are the main drawbacks, which may in turn cause insufficient bone regenerate. Patients and methods A total of 57 lengthening procedures were performed using intramedullary skeletal kinetic distractor (ISKD) nail in 53 patients (femoral = 45 and tibial = 12). Average length gain was 4.3 ± 1.6 cm. The cause of shortening was post-traumatic (n = 33), congenital (n = 20), post-tumour resection (n = 1), cosmetic femoral lengthening (n = 2) and post-correction of distal femoral varus deformity (n = 1). Results The desired lengthening was achieved in all patients. The mean follow-up period was 23 ± 12 months. The healing index for patients with normal bone healing was 1.2 ± 0.32 months/cm. Complications in femoral lengthening were superficial wound infection (n = 1), premature consolidation (n = 4) and insufficient bone regenerate (n = 11), while in the tibial lengthening, two developed equinus contractures, one had compartment syndrome following implantation of the nail and one insufficient bone regenerate. Furthermore, nine runaway nails and three non-distracting nails were present in the femoral lengthening. One non-distracting nail responded to manipulation under anaesthesia, one required exchange nailing and accidental acute lengthening of 3 cm took place while manipulating the third nail. Patients with femoral lengthening and those with insufficient regenerate had significantly higher distraction rates (P = 0.006 and 0.003, respectively). Six out of the nine runaway nails developed insufficient bone regenerate. In addition, 10.7-mm tibial ISKD nails were found to have lower rates of runaway nails compared with other used diameters. Conclusion We emphasise the rule of distraction rates above 1.5 mm/day in the development of insufficient bone regenerate. Distraction problems with these nails are mostly due to dysfunction within the ratcheting mechanism, which may be related to the diameter of the nail. New designs for mechanically activated nails with a better control mechanism for the distraction rate are required.

Control of distraction rate with an intramedullary skeletal kinetic distractor (ISKD) may be problematic and a high distraction rate may result in insufficient bone regenerate.Are distraction problems preventable when using the ISKD, and what are the risk factors for and radiologic types of insufficient bone regenerate during ISKD lengthening?We analyzed 37 consecutive ISKD femoral lengthening procedures in 35 patients with a mean age 33 ± 11 years and minimum followup of 12 months (average, 27 ± 9 months; range, 12-55 months). The average length gain was 42.8 ± 12.9 mm.Eight patients had problems during distraction: seven had "runaway nails" and one had a nondistracting nail. Insufficient bone regenerate developed in eight patients. Important risk factors were a distraction rate greater than 1.5 mm/day (9.1 times higher risk), age 30 years or older, smoking, and lengthening greater than 4 cm. Less important risk factors identified were creation of the osteotomy at the site of previous trauma or surgery and acute correction of associated deformities. We proposed a radiologic classification for failure of bone regeneration: partial regenerate failure (Type I) or complete failure resulting in a segmental defect subdivided according to a length of 3 cm or less (Type IIa) or greater than 3 cm (Type IIb).Distraction problems with the ISKD were related mostly to internal malfunction of the lengthening mechanism. A distraction rate greater than 1.5 mm/day should be avoided in femoral intramedullary lengthening. Smoking should be a contraindication for femoral lengthening.Level II, prognostic study. See Guidelines for Authors for a complete description of levels of evidence.

Removal of intramedullary nails often is relegated to younger surgeons but may be difficult and challenging. We describe difficulties with removal of an incarcerated expandable femoral nail and a new technique for retrograde mobilization of an intramedullary nail through a small infrapatellar incision. No special device was necessary for successful implant removal.Level V, therapeutic study. See Guidelines for Authors for a complete description of levels of evidence.

Summary Orthopaedic basic science data on immature skeletons are rare in the literature. Since the number of knee injuries in young humans is steadily increasing, studies on immature animals such as sheep, which can be used as model systems are becoming more and more important. However, no baseline data are available on physiologic and morphologic changes during growth in the relevant tissues. In the present study, histomorphometric changes in the tendon of the musculus flexor digitalis superficialis, the cranial cruciate ligament, the medial meniscus and the articular cartilage of the medial femoral condyle were identified in sheep between the ages of 1 and 40 weeks postnatally. Profound changes in tissue composition during growth could be observed. A high cellularity in the early postnatal period decreases to a constant lower level after 18 weeks. Similar changes during postnatal growth could be observed for blood vessel density. Also, staining of α-smooth muscle actin (SMA) and vascular endothelial growth factor (VEGF) steadily decreased. In contrast, the number of components of extracellular matrix steadily increased in all tissues. The age of 18 weeks seems to be a threshold after which the tissue composition of the observed structures remains constant in this species.

Background A common clinical concern after anterior cruciate ligament reconstruction is the expansion of the bone tunnels as seen radiographically. The etiology and clinical relevance of this phenomenon remain unclear. Hypothesis Tunnel widening results in an increased anteroposterior translation, and there are specific histologic changes due to osteoclastic bone resorption associated with this phenomenon. Study Design Controlled laboratory study. Methods Thirty sheep (age, 4 months) underwent an anterior cruciate ligament reconstruction using a soft tissue graft. Graft fixation was achieved using the EndoButton and Suture Washer. Six animals each were sacrificed at 0, 3, 6, 12, and 24 weeks after surgery. Each anterior cruciate ligament–reconstructed knee was examined by computed tomography. Anteroposterior translation was determined using a universal force-moment sensor robot. The bone surrounding the tunnel was evaluated histologically. Results The prevalence of tunnel enlargement on the femoral side was 77.3%. Animals with tunnel widening did not demonstrate increased anteroposterior translation. Widening of the femoral tunnel was significantly associated with a higher stiffness of the graft (P Conclusion In this large animal model of anterior cruciate ligament reconstruction, animals with significant tunnel widening did not suffer increased anteroposterior translation. Tunnel widening was associated with a high stiffness of the graft, graft hypertrophy, and an increase in bone volume of the tunnel wall. Clinical Relevance The present data correspond to the current opinion in humans that tunnel widening is not associated with knee instability. Further research is needed to understand the role of graft stiffness, graft hypertrophy, and the increase in bone volume in this phenomenon.

The aim of this study was to investigate, to what extent routine preoperative MRI scans could set the indications for knee arthroscopies and reduce the number of diagnostic arthroscopies. For this retrospective cohort study, 1,000 patients who had knee arthroscopies documented in 1994/1995 were compared with 1,000 patients that were treated in 2004/2005. The preoperative diagnoses that gave indications for knee arthroscopy were compared with the intraoperative findings. The congruence of preoperative diagnosis with the intraoperative findings was evaluated comparing both study populations. The number of patients who were referred to orthopaedic trauma surgeons with MRI increased from 24% to 56%. A high congruence of preoperative diagnosis and intraoperative findings was found in 49% in 1994/1995 and 55% in 2004/2005. However, regarding the most important outcome parameter, the number of diagnostic arthroscopies, no improvement was found (3% in both periods). The presented data suggests that MRI scans are not routinely necessary as an indication for knee arthroscopy, as clinical examination and plain radiograph are sufficient. However, MRI scans do allow a more detailed characterization of the expected findings and can therefore be helpful in therapy planning.

Following injury, ligaments and tendons do not regain their normal biological and biomechanical status. This study analyzed whether an injection of human bone marrow stromal cells (BMSC) or human fibroblast in a liquid fibrin matrix influences the histological results, ultrastructural morphology, mRNA expression of essential extracellular matrix proteins, and material properties of the healing tissue. Standardized full-thickness, full-length defects of the central portion of patellar tendons were created in 96 immunodeficient rats, and filled with human BMSC in a fibrin matrix (BMSC group), human fibroblasts in a fibrin matrix (fibroblast group), or fibrin matrix only (matrix group), or left untreated (defect group). Histological sections revealed more mature tissue formation with more regular patterns of cell distribution in the BMSC group, without signs of ectopic tissue formation into bone or cartilage. Mean collagen fibril diameter and relative area covered by collagen fibrils were significantly higher at 10 and 20 days postoperatively in the BMSC group compared to the defect and matrix groups, and comparable to normal tendon tissue. Further, collagen I mRNA expression, collagen I/collagen III mRNA ratio, and Young's modulus were significantly increased at 20 days postoperatively in comparison to the defect and matrix groups. In the fibroblast group, only mean collagen fibril diameter was significantly higher compared to the defect group, whereas the other biological and biomechanical parameters were not significantly improved. This study reveals that an injection of BMSC in a liquid fibrin matrix stimulates histological, ultrastructural, molecular biologic, and biomechanical parameters of patellar tendon healing, whereas injection of fibroblasts in fibrin matrix had only minor effects on the stimulation of tendon healing.

INTRODUCTION: Ruptures of the anterior cruciate ligament are being diagnosed with increasing frequency in skeletally immature individuals. It was our aim to investigate the graft remodelling process following an autologous, transphyseal reconstruction of the anterior cruciate ligament (ACL) in skeletally immature sheep. We hypothesized that the ligamentisation process in immature sheep is quicker and more complete when compared to adult sheep. MATERIALS AND METHODS: Skeletally immature sheep with an age of 4 months underwent a fully transphyseal ACL reconstruction using an autologous tendon. The animals were subsequently sacrificed at 3, 6, 12 and 24 weeks following surgery. Each group was characterised histomorphometrically, by immunostaining (VEGF, SMA), by transmission electron microscopy (TEM) and biomechanically (UFS Roboter). RESULTS: The histomorphometric analysis and presence of VEGF and SMA positive cells demonstrated a rapid return to a ligament like structure. The biomechanical analysis revealed an anteroposterior translation that was still increased even 6 months following surgery. CONCLUSION: As in adult sheep models, the remodeling of a soft tissue graft used for ACL reconstruction results in a biomechanically inferior substitute. However, the immature tissue seems to remodel faster and more complete when compared to adults.

Until now, there has been no in vitro model that duplicates the environment of bone marrow. The purpose of this study was to analyze proliferation and differentiation of human bone marrow stromal cells (hBMSC) under the influence of continuous perfusion and cyclic mechanical loading. hBMSC of seven individuals were harvested, grown in vitro, and combined. 10(6) hBMSC were seeded on a bovine spongiosa disc and incubated in a bioreactor system. Cell culture was continued using three different conditions: Continuous perfusion (group A), 10% cyclic compression at 0.5Hz (group B) and static controls (group C). After 24h, 1, 2, and 3 weeks, we determined cell proliferation (MTS-assay) and osteogenic differentiation (osteocalcin ELISA, Runx2 mRNA). Tenascin-C mRNA was quantified to exclude fibroblastic differentiation. In groups A and B, proliferation was enhanced after 2 weeks (48.6+/-19.6x10(3) (A) and 44.6+/-14.3 x 10(3) cells (B)) and after 3 weeks (46.6+/-15.1 x 10(3) (A) and 44.8+/-10.2 x 10(3) cells (B)) compared with controls (26.3+/-10.8 x 10(3) (2 weeks) and 17.1+/-6.5 x 10(3) cells (3 weeks), p

Background.Artificial calcanei, fresh-frozen cadaver specimens, and embalmed cadaver specimens were compared in experimental testing under biocompatible loading to clarify the biocompatibility of artificial calcaneal specimens for implant testing.Methods.Two different artificial calcaneal bone models (Sawbone™, Pacific Research Laboratories, Vashon, WA, and Synbone™, Synbone Inc., Davos, Switzerland), embalmed cadaver calcaneal specimens (bone density, 313.1 ± 40.9 g/cm2age, 43.8 ± 7.9 years), and fresh-frozen cadaver calcanei (bone density, 238.5 ± 30.0 g/cm2age, 44.4 ± 8.2 years) were used for testing. Seven specimens of each model or cadaver type were tested. A mechanical testing machine (Zwick Inc., Ulm, Germany) was used for loading and measurements. Cyclic loading (preload 20 N, load was increased every 100 cycles by 100 N from 1,000 to 2,500 N, 0.5 mm/s) and load to failure (0.5 mm/s) were performed. The loads were applied through an artificial talus in a physiological loading direction. The displacement of the posterior facet in the primary loading direction was measured.Results.The four different specimen groups showed different stability and different displacement in the primary loading direction during cyclic loading. The variation of the maximal displacement in the primary loading direction for the entire cyclic loading was higher in artificial specimens than in the cadaver specimens.Conclusions.Artificial calcanei (Sawbone™, Synbone™) showed different biomechanical characteristics than cadaver bones (embalmed and fresh-frozen) in this experimental setup with biocompatible cyclic loading. These results do not support the use of artificial calcanei for biomechanical implant testing. Fresh-frozen and embalmed specimens seem to be equally adequate for mechanical testing. The low variation of mechanical strength in the unpaired cadaver specimens suggests that the use of paired specimens is not necessary.

Excision of damaged meniscal tissue whereby the mechanical obstacles to joint movement are eliminated. As much functional, intact meniscal tissue should be retained as possible. Resection of only the bare minimum.Symptomatic, irreparable lesions of the meniscus due to trauma or degeneration.Reparable lesions of the meniscus. Local skin affections.Introduction of the arthroscope through an anterolateral or central portal. The instrument portal is positioned in accordance with the situation of the meniscal lesion to be treated. The tissue to be excised is either broken into fragments with different punches or resected en bloc.Functional postoperative management without immobilization. Full loading on the leg.Very good and good clinical results can be achieved in the short and long term after arthroscopic partial meniscectomy. In a study by Burks et al., 88% of 146 patients with stable knee joints had a very good or good result 14.7 years after partial meniscectomy. 95% of 57 patients were satisfied or very satisfied with the result 12 years after partial medial meniscectomy. A degenerative meniscal tear, axial deformity, higher age, and anterior cruciate ligament insufficiency are factors associated with an increased rate of arthrosis in the long term.